Method and means for impeding the seepage or flow of water



P. BECHTNER 2,277, 8 METHOD AND MEANS FOR IMPEDING THE S'EPAGE OR FLOWOF WATER March 24, 1942.

Filed Nov 19 56 INVENTOR IDAUL BECHTNER BYg ATTORNEYS I MJ Jdescription.

Patented Mar. 24, 1942 UNITED STATES [PATENT OFFICE METHOD MEANS FORIIVIPEDING THE SEEPAGE OR FLOW OF WATER- Paul-Bechtner, Chicago, Ill.assignor to American Colloid 00., Chicago, 111., a corporation of SouthDakota Application November 5, 1936, Serial No. 109,245

13 Claims.

This invention relates to improved methods and means for impeding theflow of water and for reinforcing structures to prevent the seepage ofwater therethrough. The seepage and flow of water through earthworks,dams, ma-

sonry constructions, water barriers and the like causes untoldeconomical loss, much of which can be prevented by the. invention hereindescribed.

Seepage through water barriers, such as dams,

cofierdams, and water-retaining walls may be caused by any of severalconditions. The bedrock may not be impervious to flow. The circumstancesmay require that the barrier be placed on porous bodies of materialssuch as sand shrinkage of the setting concrete away from the,

walls against which it is cast. Such leakage, once started, sometimesresults in destruction of the wall and complete release of the backed-upwater.

Similar problems are encountered in efforts to exclude water from coretrenches, excavations and "foundation walls of buildings and to confinewater to prescribed ditches or channels, In fact, these are but a few ofthe many circumstances under which it is highly desirable yet difliculteffectively to prevent the flow or seepage of water. I

An object of my invention is to Provide improved methods and means forinhibiting the seepage of water through pervious structures and forsafeguarding against seepage or flow through structures that arenormally impervious but ,capable of developing leaks.

Another object is to provide improved barriers which are constructedbetter to insure against water seepage or flow.

Another object of my invention is to provide such methods and meanswhich are-permanently effective regardless of shrinkage, cracks, or

shocks and distortions caused by subsidence,

earth movements and the like.

Another'object is to provide special methods and means by which it ispossible to correct existing conditions of seepage or flow withoutrequiring freedom from contact with the water.

Stillcfurther objects and advantages of the invention will be apparentfrom the following I have discovered that water seepage may be preventedand that structures of various types may be safeguarded against-leakageby blocking the path of. flow of .the water with bentonitic or highlycolloidal clay which possesses the capacity to swell and gelatinize uponcontact with water. The type of clay best suited for the present'purposes is the true bentonite obtained in regions of Wyoming and SouthDakota, although other highly colloidal, or bentonitic clays whichpossess the property of swelling and gelatinizing in water to asubstantial degree are also useful. The degree of their efiectlVenessdepends upon the closeness with which this swelling prop-- 15. ertycorresponds to that of true bentonite.

True bentonite is a material consisting principally of the mineralMontmorillonite and occurring naturally in combination with about to 45%water. For commercial use this mate- 20 rial is dug, dried to containabout 9% moisture,

and then granulated or powdered. Some physical characteristics whichdistinguish bentonite from other clays are its permeable texture and itsextremely small grain size. From 65 to 70% of the grains of a Wyomingbentonite are finer than .2 micron; over 85% are finer than 2 microns.-These grains or particles, when wetted, adsorb films of water that arethicker than the films which form on other clay-like materials,

and after 'the bentonite has been wetted the water cannot be expelled,even at high pressures.

The strong adsorptive power of commercial bentonite, which will adsorbalmost five times its weight of water, is therefore partiallyattributable to the preponderance of extremely small grains orparticles, providing tremendous surface area for the exertion ofadsorptive powers, and the film retaining capacity of these particles.

w Commercial bentonite swells, when contacted with water, as much as 10to 20 times its dry volume. One factor which causes this swelling is theseparation of the small particles by the water films adsorbed thereon.Another is the distinctive nature of the particles themselves,

which are composed of minute plate-like struc tures that possess thepeculiar property of allowing water molecules to penetrate their crystallattice. The crystal structure itself is thus expanded. A third factoris the mutual repulsion of the particles, due to like negative polarity.3

In its swollen condition bentonite has several advantageous properties;it will carry materials in suspension; it exerts a cohesive effect; whenleft quiescent it forms a permanent gel the viscosity of which increasesupon aging. An important aspect of the swelling of bentonite which Ihave discovered is that it will swellv only to the extent necessary toflll available space, without exerting substantial pressure whenconfined against further swelling. Another important quality is thatrepeated drying and contraction of swollen bentonite in no way impairsits capacity to swell again upon renewed contact with water. Theseproperties make it an ideal material for incorporation in a dry orslightly moist state into dams and other water barriers, at points whereleakage possibilities occur, so that in case cracks or other leakagedevelop the bentonite will come into contact with the leaking water andswell to stop the leak but will not create pressure which might causefurther breaks.

I have discovered that a blanket or wall of bentonite which possessesthe capacity to swell upon contact with water will permanently resistseepage or flow of water therethrough. When the bentonite is contactedwith water it swells to fill available voids or spaces. Thereafter it isimpervious, and it remains impervious to water as long as water ispresent. If water is not con-' tinuously present the bentonite maycontract as it dries, but its resistance to seepage is immediatelyrestored upon renewed contact with water.

I have found also that bentonite confined within masonry structures orthe like, when wet,

does not exert swelling pressures suflicient to harm the structures inany way, yet it forms an impervious seal with the confining surfaces.Furthermore, the bentonite, either in dry or wet swollen condition, maybe subjected to shocks, earth movements or subsidence without destroyingits sealing power. The swelling capacity of the material is completelyexhausted only when it is suspended freely in many times its volume ofwater. Accordingly, by utilizing a blanket or wall of bentonite to blockthe flow or seepage of water I am able to effect permanent impedence ofsuch flow or seepage under many difficult conditions. Appropriatecombinations pf bentonite and strength giving structure produce barriersthat are resistant to water under great pressure.

Several preferred modes of practicing my invention are illustrateddiagrammatically in the drawing, wherein Fig. 1 is a diagrammatical planview of an embodiment of my invention in which inserts of bentonite areemployed to reinforce a dam against water seepage.

Fig. 2 is a diagrammatical vertical section through a portion of a damat a joint between the main wall of the dam and the-abutment.

Fig. 3 shows an application of my invention similar to Fig. 1 in whichthe bentonite is placed in wells adjacent the connection of the mainportion of a dam with the wings thereof.

Fig. 4 represents a vertical cross section of another type of damconstruction,.in which a blanket of bentonite is interposed between thebedrock and the bottom of the dam.

Fig. 5 illustrates the application of the invention to the closing of amine or conduit against the flow of water therethrough.

Fig. 6 illustrates the use of a blanket of bentonite to protect thefoundation wall of a building against water seepage.

Fig. '7 is a partial view, in vertical section, of a floor provided withan underlying layer of bentonite.

Fig. 8 represents, in cross section, a trench or ditch bordered by ablanket of bentonite in such manner as to prevent the seepage of waterfrom Fig. 10 shows another embodiment of a structural unit.

In Figures 1 to 4, inclusive, I illustrate improved dam constructionsutilizing the principles of my invention. Within the dam structure atpoints likely to be affected by seepage, cracks or the like, I provideinserts of bentonite so that water seeping through the structure willcontact the bentonite.

For example, in the construction of Figure 1, the dam I0 faces againstabutment walls I2 and I3, and at the meeting surfaces of these memberswells l4 and I5, extending for the height of the dam into the concreteor other material of which the dam is formed, are provided. The wellsare filled with a dry bentonitic clay having the capacity to swell andgelatinize upon contact with water. Figure 2 may be considered as asection taken vertically along the axis of the dam and through the wellIS. The abutment I3 is illustrated as comprising a concrete portionpositioned on rock at I8. Well I5 extends, for the height of the dam,across the joint I 6 between the main wall I 0 and the abutment, and itis filled with bentonite as indicated at ll.

Figure 3 represents an arch-like dam having a central wall 20, wings 2|and 22, and, at the joints between the wall 20 and the wings, wellswhich confine masses 23 and 24 of bentonitic clay. In Figure 4, a dam 25positioned on bedrock 26 is provided with an insert of bentonitic clayat 21, bridging the seam between the dam and the rock.

Dams constructed with inserts of bentonite at points susceptible toleakage are surprisingly resistant to the passage of water. Theshrinkage of setting concrete, earth movements, contraction andexpansion due to changing temperatures, etc., are likely to result inwater permeable seams and crevices. The presence of a mass of bentoniteat such points, however, provides permanent protection against seepage.When the confined bentonite is contacted with water which has traversedthe structure to the location of the bentonite it immediately adsorbs.

water, swells enormously, and forms a gelatinous mass which itself isimpervious to water and provides an impervious seal with the confiningwalls of the structure.

Although the insert 21 of bentonite in Figure 4 is illustrated assurrounded by dam structure and bedrock, other arrangements may befollowed without sacrificing results. Substantially dry bentonite isnotable for its extreme density and compressive strength when packedinto a compact mass. Wherever the bentonite is subject to flowing watercurrents which would carry away the gels as they formed this erosion maybe prevented bymaintaining a layer of sand or other erosion resistantmaterial between the bentonite and the flowing water. The bentonite thenforms a tight-filter-cake on the surface of the sand.

Figure 5 is a diagrammatical showing of a construction which iseffective to block the flow of water through mines, or water conduits ingeneral. A pair of spaced forms or bulkheads 32 and 34 extends across amine shaft 30, and a mass of bentonite or similar colloidal clay islocated at 35 between these forms. The forms may be of wood, masonry orany other suitable material. 'The bentonite may be in finely digidedform, or in the form of blocks or bricks, or it may be combined withother material, for example, sand or gravel.

In the use of this embodiment of the invention distinct advantages areobtained as compared with concrete walls and other types of barriersheretofore employed for the same purposes. The leakage permitted by theshrinkage of concrete walls away from the walls of a mine or conduitduring the setting of the concrete is completely avoided. Whenever theform 32 allows backed-up water at 38 to contact the bentonite at 36, thebentonite first contacted adpermanently resistant to seepage. The sameeffeet is produced whether the water contacts the bentonite along thewalls of the mine or conduit or remote from the walls.

A characteristic feature of this and the other embodiments of theinvention is that the swelling sorbs water, swells and forms a gel whichis penetration are obtained by the use of pure bentonite or purebentonitic clay, I have discovered also that the resistance of the massto high water pressures may be increased by employing mixtures ofbentonite or bentonitic clay and other granular materials, for example,sand. For

. example, when a mixture of equal parts of benof only a small portionof the mass of bentonite,

the portion first contacted with water, is usually effective to blockseepage through'to other portions of the mass. Thus these otherportionsu'etain their full capacity to absorb and swell and blockfurther flow or seepage in the event that the first gel formation shouldbe disturbed.

Another important advantage .is that the ex"- pense and care incident tothe. provision of barriers such as concrete walls are avoided. Theforms32 and 34 need not be impervious to water; it is sufiicient that theygive strength to the barrier and that form 34 include no openingspermitting escape of the bentonite therethrough. The

be removed easily; whereas the destruction of a barrier composed ofmasonry is a difficult task.

My invention is also applicable to impede the blanket of bentonite isinterposed as indicated at 44. As in the other embodiments describedabove, the bentonite swells when contacted with 5 water and forms animpervious barrier which prevents the water from seeping to and throughor around the wall 40. An arrangement such as that shown in Fig. 7 isparticularly suitable for the ground floors of buildings placed in low,damp ground. A blanket 41 of bentonite is placed on the base 46 for thefioor, and the fioor 48, which may be of concrete or any othersuitablematerial, is applied over the bentonite.

Figure 8 illustrates a mode of applying the invention to the preventionof seepage from a ditch or the like formed in pervious soil. In theBetween the foundation wall 40 of a construction of the ditch a blanket52 of bentonite As the bentonite is contacted woth water it swells toform an impervious gelatinous barrier, one

tonite and beach sand is poured into a T-shaped section of 3 inch pipeto a height of 20 inches in the longer arm of the T and lightly tampedtherein, the mass is not moved by continuing water pressures of 1000 lb.per square inch, and the water penetrates the mass a distance of onlyabout 5 inches. W

An important advantage of the invention results from the variety ofmethods which may be employed to form the seepage-resistant mass ofbentonite. In one embodiment ordinary commercial powdered or granulatedbentonite may be used. Even when loosely put in place as by pouring,such finely-divided material provides a permanent barrier againstseepage, since the swelling power of dry bentonite is so great thatvoids in the mass are blocked upon contact with water. The physicalstrength of such a mass may be increased by tamping or packing thebentonite in place.

Under som circumstances of use it is impractical to provide temporary orpermanent supporting means for the bentonite before forming the mass; 1.e., the bentonite must be placed first. For example, in sealing a wallfrom the outside earth the most practicable procedure may be to form themass of bentonite adjacent the wall and then fill in the earth.According to another embodiment of my invention this may be accomplishedby incorporating the H bentonite with from one to one and a half timesas much water to form a stiff putty-like mass which is sufiicientlycohesive to adhere to rough I ,where water is present by fashioning itroughly into bricks or blocks each having a quantity of dryfinely-divided bentonite in its interior. Similar results may beobtained, as illustrated in Figure 9, by forminga bricklike body Ill ofhentonite which has been moistened only sufficiently to produce slightcoherence and then contacting the outsides of the body with water, as bydipping or spraying. The water does not,- penetrate far into the bodybut causes the bentonite at the surfaces thereof to swell and form acohesive sheath or enclosure as indicated at '|2, which strengthens theunit so that it can be handled and placed in position. Another suitableproagainst leakage I cedure (see Figure is to use a fabric enclosure,for example, a paper cartridge as indicated at 80, filled with drybentonite 82. Still another, which is useful under circumstancesprohibiting the construction of a solid blanket of bentonite, as in theprevention of seepage through water covered porous rock or gravelstructures, is to force a heavy pumpable suspension of bentonite intothe structure and thus build up a blanket of bentonite in the path ofseepage.

The' invention is not limited to the specific illustrative uses andmethods of use described hereinabove, although these possess their ownindividual advantages. When dry or swellable bentonite is applied toexpansion joints, shrinkage joints, or adjacent corners where cracks arelikely to develop in concrete dams, or when used in any water barrierwhere, upon coming in contact with water, it will swell and stop theleakage, this is within the scope of my invention, and inasmuch as Ihave discovered that bentonite can be used in this manner withoutdeveloping appreciable pressures on swelling, innumerable further usesfor bentonite in sealing water barriers, based on the principles I havedisclosed, will occur to those skilled in this art.

I claim:

l. A dam comprising a masonry wall positioned on a supporting bed andabutting against end abutments, said masonry having a compartmenttherein at a point susceptible to leakage, and a compact mass ofswellable bentonite confined within said compartment.

2. A dam comprising a masonry wall positioned on a supporting bed andabutting against end abutments, a compartment extending along the jointbetween said wall and an abutment, and a compact mass of swellablebentonite filling said compartment.

3. A water dam comprising a concrete dam structure having pockets ofswellable bentonite therein.

4. A self-sustaining structural unit for the for mation of barriersimpervious to water comprising finely divided, slightly moist swellablebentonitic clay in the interior thereof and wet bentonitic clayconstituting a cohesive enclosure therefor.

5. The method of making structures resistant to seepage or flow of watertherethrough which comprises positioning a mass including swellablebentonite across the path of such seepage or flow and confining saidmass between spaced rigid supporting structures, said mass being ofsufficient thickness and bentonite concentration to swell and formadjacent the water face, when contacted by the water, a supported,water-impervious barrier of swollen gelatinous bentonite merging intoswellable bentonite.

6. The method of preventing flow or seepage from bodies of water whichcomprises forming and supporting and confining across the water path acompact blanket of finely-divided, substantially dry swellablebentonite-of sufiicient thickness and bentonite concentration to swelladjacent its face upon contact by the water and form across said path awater-impervious barrier of swollen bentonite merging into a reservemass of substantially unswollen bentonite.

7. The method of making structures such as dams, bulkheads, masonrywalls and like water barriers impervious to seepage or flow therethroughfrom bodies of water, which comprises providing space in the structureacross the path of such seepage or flow and filling into and confiningwithin said space a mass of substantially dry, finely-divided swellablebentonite mixed with sand, said mass being of suflicient thickness andbentonite concentration to form across said path, upon contact by thewater, a water-impervious barrier of swollen bentonite adjacent its facemerging into substantially unswollen bentonite within the mass.

8. A water barrier comprising rigid supporting structures having spacetherein in the path of water seepage or flow and a compact mass offinely-divided swellable bentonite confined across said path in saidspace, said mass being of sufiicient thickness and bentoniteconcentration to swell at its face and form across said path, whencontacted by water, a water-impervious barrier of swollen bentonitemerging into substantially unswollen bentonite.

9. The method of blocking the flow of water under pressure through adeterminate path which comprises restraining the water from a part ofsaid path, forming across said path at said part a compact massincluding substantially dry swellable bentonite of sumcient thicknessand bentonite concentration to swell adjacent the water face and formacross said path a waterflow from a body of water through a determinateV path comprising rigid supporting structure having space therein acrossthe water path and a compact mixture of finely-divided swellablebentonite and granular material confined across said path in said space,said mixture being of sufficient thicknessand bentonite concentration toswell at its face and form across said path, where contacted by water, awater impervious barrier of swollen bentonite marging into a reservemass of substantially unswollen bentonite.

11. The method of preventing flow or seepage of water through rigidstructures susceptible to water penetration which comprises placing andsupporting adjacent a side of such structure and across the path ofwater penetration a compact blanket including finely-divided, swellablebentonite and of sutficient thickness and bentonite concentration toswell at its face upon contact by the water and form across said path awater impervious barrier of swollen bentonite merging into swellablebentonite, and providing means adjacent the face of said blanket forholding the same in place.

12. A bulkhead or the like for preventing water flow through adeterminate path comprising substantially rigid structures spaced apartand extending across the water path, said structures being susceptibleto water penetration, and a compact mass of finely-divided bentonite,confined within the space between said structures.

13. A bulk head or the like for preventing water flow through adeterminate path comprising substantially rigid structures spaced apartand extending across the water path, said structures being susceptibleto water penetration, and a water-impervious mixture of finely-dividedbentonite and sand confined within the space between said structures.

PAUL BECHI'NER.

